Do not process a message if it is an Out of Office response
Extract FactCheckEmail to hide Out of Office checking implementation
Should be comparing based on the to_s value
Add email header tests that allow state progression.

Factor out duplicate code.
Use correct boolean || operator
Add 'auto-generated' as a value to check for out of office replies
Add check for Return-Path header.

Since Return-Path is blank for Out of Office replies (checking factcheck
mail responses), this would be indistinguishable from the field not being
present if just using `mail[header].to_s`.

As well as checking the value of the header, I've added a check that
the header key returns a Mail::Field too. If the header is not present
NilClass is returned.
Unnecessary use of map then any?
Remove batch publishing feature.

This is redundant now that we have scheduled publishing.
Merge pull request #193 from alphagov/remove_batch_publishing

Remove batch publishing feature.
Bump content models

To pick up validation of Edition version_numbers
Migration to fixup duplicated version_numbers

This is necessary to allow the new db index to be created.
Audocreate indexes in tests.
Merge pull request #192 from alphagov/out-of-office-does-not-trigger-fact-check-received

Out of office does not trigger fact check received
Merge pull request #195 from alphagov/version_number_validations

Update content models to get version_number uniqueness validation.
Do not allow attempts to create more than one draft